In battery packs provided with one or multiple secondary batteries in the known related art, when a battery abnormality is detected, charging of the secondary battery is stopped, and the secondary battery is connected to a resistance to automatically discharge the secondary battery (for example, see Patent Documents 1, 2, and 3). When such an abnormality occurs, because the energy stored in the battery pack is discharged, it is possible to maintain the battery pack in a safe state.
Patent Document 1:    Japanese Unexamined Patent Application, Publication No. 2001-298867
Patent Document 2:    Japanese Unexamined Patent Application, Publication No. 2003-142162
Patent Document 3:    Japanese Unexamined Utility Model Application, Publication No. HEI-6-57050.